#include <bits/stdc++.h>
using namespace std;

const int N = 100;
long long f[N];
long long sum[N];

int main()
{
    f[1] = 1;
    for (int i = 2; i <= 80; ++i)
    {
        f[i] = f[i - 1] + f[i - 2];
    }

    for (int i = 1; i <= 80; ++i)
    {
        sum[i] = sum[i - 1] + f[i];
    }

    int from, to;
    while (cin >> from >> to)
    {
        cout << sum[to] - sum[from - 1] << endl;
    }
    return 0;
}